Specimens must be specially prepared for viewing with the electron microscope, and which involves sophisticated processing of the very small and thin tissue to be examined. It is necessary to maintain cleanliness while subjecting the specimen to a multiplicity of different solutions, allowing for these fluid changes, and holding the specimens accessible to said solutions and for subsequent plastic embedding. This invention relates, therefore, to a wide range of dehydrating and impregnating schedules or processes and provides therefor an apparatus that is manually operable and which can be produced and utilized most economically. Although such processes have been conducted both manually and by automation, manual processing with conventional test tubes, beakers and trays is time consuming and wasteful of the solutions, while the automation of such processing is extremely costly and also wasteful of the solutions and accessories such as tubes and containers. With the present invention, the parts of the apparatus are permanent for the most part and are cleaned for reuse, and those parts which are subject to deteriorization or damage are of minimal complexity and are expendable at low cost. In practice, small beakers are employed for containing the solutions employed for fixation, staining etc. to final dehydration and embedding of the biological tissue. Plastic embedding is increasingly used for electron microscopy and the procedures referred to herein therefore require cleanliness, precision and reproducibility, while taking into account the incompatability of solutions with each other and of the viscosities of solutions used in infiltration and embedding.
Conventional laboratory techniques involve the use of test tubes and like vials, made of glass adapted to be sterilized for cleanliness. Heretofore, the specimen to be embedded has been dropped into the test tube so as to rest upon the bottom thereof where it is very much inaccessible for removal, a difficulty involved in ordinary manual processing but obviated in automated processing at the expense of solution waste. However, with the present invention open ended tubes are provided to carry sieve cups that support the specimens to be processed. The cups are easily removed from the tubes for ready access to the specimens which are necessarily very small for ultra thin sectioning. Accordingly, it is an object of this invention to provide a tube and cup combination in place of the conventional test tube or vial, and which allows the ingress and egress of solutions to engulf and receed from the specimen, as may be required.
Conventional laboratory techniques involve the use of beakers and the like, also made of glass adapted to be sterilized for cleanliness. Heretofore, the specimens have been immersed by filling test tubes or vials, trays and/or troughs and the like; with a wasteful volume of solutions. With the present invention, one or more small beakers is employed and means is provided to suspend the aforesaid tube and cup combination therein, for immersion of the specimen by virtue of ingress of solutions through the sieve of the cup. As will be described, the solution level is minimal and immersion of the specimen is nevertheless ensured. Accordingly, it is another object of this invention to provide means carried by the header to place the cups at a determined level for adequate immersion of said specimen. With the present invention, said means is a multi purpose header as will be described, to suspend the tubes, and to provide access to both the beaker and the tubes.
Laboratory procedure involving biological specimens of the type under consideration requires simultaneous processing of a multiplicity of such specimens. Accordingly, it is another object of this invention to provide means by which one or a multiplicity of the tube and cup combinations can be manipulated for subjection to the various solutions and embedding of the specimens supported therein respectively. With the present invention, said means is a base or holder for the one or a multiplicity of sieve cups per se into which the specimens are placed and which subsequently receives the tube or tubes that project upwardly to be suspended by the aforementioned header.
It is still another object of this invention to provide a combination of apparatus as thus far described, the elements of which are assembled and disassembled by light manual pressures, the sieve cup and header elements being fabricated of supple plastic material unaffected by the solutions involved and which press together for reliable integrating when in operation, and readily separable for removal of the specimens for embedding and for cleaning, all as circumstances require.
Having provided for access to the sieve cup, as above described, it is an object to provide for handling thereof and removal of the same from the aforesaid holder, or to replace the same thereon. To this end the tube or tubes are guided by a plate slideable along said tube or tubes to maintain the positions thereof with respect to each other and to the holder and header respectively.
It is an object to assemble as many specimen cups as may be required and to simultaneously handle a multiplicity thereof for processing in relatively small vessels containing the liquids into which specimens carried thereby are to be immersed. In carrying out this invention, the liquid volumes are maintained at a low level and are consequently small while entering the tubes to immerse the specimens by passing through the sieve feature of the cups that support the specimens. Therefore, it is characteristically the raising and lowering of the sieve cups and the orientation of the multiplicity thereof which controls logical processing of numbers of specimens immersed in a plurality of varied liquids used in this preparation for and/or plastic embedding and the like. It is also another feature and an object of this invention to include tooling as part of the apparatus whereby the mesh gradient of the sieve cup is selective as circumstances require, the said tooling involving the cup elements as they are installed in the holder for use.